One of the examples of a transmission system that transmits and receives content data among a plurality of transmission terminals through a relaying apparatus is a television conference system in which a television conference is held though a communications network such as the Internet. The need for such a television conference system has been increasing because of the recent demand for reduction in cost and time taken for business trips. In such a television conference system, a plurality of television conference terminals, which are examples of the transmission terminals, are used. A television conference can proceed by transmitting and receiving image data and voice data among the television conference terminals.
There are inadequate environments for a television conference, such as private places including home. As a countermeasure for a television conference held under such an environment, a transmission terminal has been developed that acquires a state of the environment under which another transmission terminal on the other parties' side is installed and controls image communications or voice communications (refer to Japanese Patent Application Laid-open No. 2008-131412).
The transmission terminal disclosed in Japanese Patent Application Laid-open No. 2008-131412, however, controls the image communications or the voice communications simply by taking into consideration the surrounding environment of the transmission terminal on the other parties' side, but does not control the image communications by taking into consideration the image communications state of the transmission terminal on the other parties' side. That is, the transmission terminal disclosed in Japanese Patent Application Laid-open No. 2008-131412 does not control the image communications by taking into consideration the image communications state, such as the transmission terminal on the other parties' side has a voice communications function but has no image communications function or the transmission terminal on the other parties' side has an image communications function but is not performing image communications. Accordingly, when the transmission terminal performs image communications with the transmission terminal on the other parties' side in the above-described state, the image communications will run to waste because the transmission terminal on the other parties' side cannot respond to the image communications.